This invention relates to screwdrivers of the type incorporating, within a single tool, screw bits which can be alternatively used with either slotted or Phillips headed screws.
Screwdrivers of this type are generally known. U.S. Pat. No. 4,328,721, which is the closest prior art known to me, shows a screwdriver including a tubular shank terminating at its leading end with a Phillips head screw bit. Disposed within the tubular shank, and moveable therewithin, is an elongated, rectangular blade terminating at its leading end with a slotted screw bit. The Phillips head screw bit, while otherwise conventional, includes an axially extending rectangular slot which extends entirely through the bit and opens into the interior of the shank. The elongated blade within the shank is aligned with the slot through the Phillips bit, and means are provided for advancing the leading end of the blade through and beyond the Phillips bit, thereby exposing, for use, the slotted screw bit at the end of the blade. Means are also provided for withdrawing the blade rearwardly of the Phillips bit, allowing use of the screwdriver as a Phillips screwdriver.
The blade advancing means includes a latch means which is disposed within the handle of the screwdriver. This allows for but a single exposed length of the exposed blade, i.e., the length of the exposed blade is not variable by the user, and the handle of the screwdriver is more complex and expensive than that in a conventional, single purpose screwdriver.
The present invention is directed to a screwdriver of the type aforedescribed, but including improvements in the means for advancing and retracting the interior blade, and including structural changes for increasing the strength of the screwdriver while reducing its complexity and cost.